The sleep-deprived, often disorienting way a person feels after working on so many impending deadlines their life has become a blur, usually made possible by the regular consumption of several litres of caffeinated beverage in short amounts of time.
Employer: "Have you been here all night? You look like shit!"
Employee: "Yeah, a bad case of brain-lag..."
{employer leaves cubicle}
Employee: "...bastard."
This usually occurs early in the morning, and the period you can be affected by it will extend the less sleep you got the previous night. During a Brainlapse, you forget where you were going, what you were doing and sometimes who you are.
Brainlapsing is usually accompanied by a halt in movement until the Brainlapse has passed.
Person 1: Hey, Person 2.
Person 2: ...
Person 1: Hello?
Person 2: Wha-
Person 1: ...
Person 2: Oh, right. Sorry, I had a Brainlapse. I was up late last night.
A derivative of brain and fag, brainfag can be used to convey multiple meanings.
1) When your brain stops thinking.
2) When you come up with a brilliant idea to an extent that you think of making love to your own brain/own gender!
3) When your brain is on a roll and you are constantly emitting great ideas.
eg. of 1) “Dude, I am so brainfag-ed!”
eg. of 2) “Man, I am such a brainfag. Look at this piece I have just written!”
eg. of 3) “Look at me brainfag-ing!”